Turtles are carrying - and potentially spreading - superbugs across the Great Barrier Reef after being exposed to human and agricultural waste, researchers warn.
A study of 73 green sea turtles has revealed many were carrying drug-resistant enterobacteriales, a type of bacteria including E. coli, which can lead to serious infections in humans.
Almost 80 per cent of the bacteria was resistant to at least one class of antibiotic, while nearly a third were resistant to multiple drugs, James Cook University researchers discovered.
The bugs found on turtles collected near Cockle Bay, Toolakea and Ollera Creek Beaches, were resistant to all 12 types of antibiotic, including penicillin.
"The presence of (drug resistant) enterobacteriales with the potential to infect humans and other animals in the GBR is an important finding that indicates the possible marine microbial pollution in proximity to large urban development," the researchers wrote.
Microbiologist Shamim Ahasan has been testing green sea turtles for drug-resistant buggs. Photo: Supplied
Microbiologist Mohammad Shamim Ahasan, a PhD student leading the study, said the risk of a human becoming infected from contact with a turtle was very low but that anyone who ate undercooked turtle meat was at risk.
"If the turtle is infected with that bacteria and the meat is not properly cooked then there is a possibility to transmit the harmful bacteria and even the antibiotic resistant gene to humans," he said.
Mr Ahasan said the turtles that were found closer to Cockle Bay were more likely to carry bugs resistant to drugs like ceftiofur, an antibiotic used by veterinarians.
"It can be human faeces, or animal faeces, or livestock contaminants, agricultural or urban runoff, things we use as insecticides," he said. "These things come into the ocean and the turtle are picking up the bacteria that is resistant to these antibiotics from those places.
"The turtles that we have caught in the pristine areas are less likely to have antibiotic resistance."
The researchers speculated the turtles may be picking up the bugs on contaminated beaches overseas and bringing them to the reef.
"We are dealing with turtles who are highly migratory by nature so they can pick up the bacteria from other South Pacific countries," Mr Ahasan said.
"There are other countries that indiscriminately use antibiotics in their livestock, in agriculture, and even humans."
Countries in the region should work together to develop a protocol for the use of antibiotics, he said, adding the study was preliminary and more research was needed to better understand the problem.
The study was recently published in Marine Pollution Bulletin.